Apparatus for attaching backing to a die

ABSTRACT

Profiled internal and/or external cuts, particularly window openings in blanks of envelopes or the like are provided in moving blanks or webs of paper and the like by a rotary punching die the cutting edges of which are shaped as an enveloped cylinder and/or a rotary mating segment cooperating with the die to support the blanks or webs during the cutting. The invention is particularly characterized by the provision of a layer of curable synthetic resin firmly fixed to the underside of the punching die or of the mating segment.

United States Patent Heyden [451 Aug. 29, 1972 [54] APPARATUS FOR ATTACHING BACKING TO A DIE [72] Inventor: Guenter Heyden, Neuwied, Germany [73] Assignee: Winkler & Duennebier, Neuwied am Rhine, Germany 22 Filed: Sept. 23, 1970 21 Appl.No.: 74,575

[30] Foreign Application Priority Data Sept. 25, 1969 Germany ..P 19 48 506.4

[52] US. Cl ..76/4, 425/ 1 17 [51] Int. Cl ..B2lc 5/20 [58] Field of Search.........76/4, 107 R; 425/117, 125, 425/406 [56] References Cited UNITED STATES PATENTS 3,280,682 10/1966 Sauer ..93/58.2 X

Primary Examiner-Bernard Stickney Attorney-Richards & Geier [57] ABSTRACT Profiled internal and/or external cuts, particularly window openings in blanks of envelopes or the like are provided in moving blanks or webs of paper and the like by a rotary punching die the cutting edges of which are shaped as an enveloped cylinder and/or a rotary mating segment cooperating with the die to,

support the blanks or webs during the cutting. The invention is particularly characterized by the provision.

of a layer of curable synthetic resin firmly fixed to the underside of the punching die or of the mating segment.

3Claims, IZDraWingFigul-es Patented Aug. 29, 1972 6 Sheets-Sheet 2 if 5 w w \6 f 4 f h, l i Vi F ii :5: r m V In entor GUenZer He cyen 8g ATTOILN S Patented Aug. 29, 1972 3,686,989

6 Sheets-Sheet 5 lnQcnlor Guen fe r- Hayden B oL-woz gw ATTOILN ELS Patented Aug.29, 1972 3,686,980

\- 6 Sheets-Sheet 5 Invent r a (llc u vg ATTO (L 55 Patented -Aug. 29, 1972 6 Sheets-Sheet 6 Fig. 11

I Inventor Guenfer He clan 65 ob'idw 'dlsfgmr- AT OfLNESS APPARATUS FOR ATTACHING BACKING TO A DIE DESCRIPTION OF THE INVENTION This invention relates to rotary punching dies having cutting edges formed in accordance with the shape of the cuts which they must carry out and/or hard rotary mating segments having outer cylindrical surfaces and cooperating with the punching dies. The invention is particularly concerned with devices of this type wherein the cutting edges of the punching die produce shaped cuts, such as cut-out window openings in a strip supported by the mating segment or in individual blanks of paper and the like.

In prior art punching dies are known which cooperate with a rotary hard mating segment or a rotary hard mating cylinder, or which cooperate with a stationary hard abutment, such as a strip of hard metal.

Known rotary punching dies have a hollow cylindrical underside and are mounted by screws on a supporting cylinder. The cutting edges of these punching dies are disposed along a cylindrical surface which is concentric to the supporting cylinder and, for example, for cutting window openings in blanks for window envelopes, these cutting edges have the shape of a closed rectangle. For this purpose, the entire punching die is machined from a tubular steel segment, hardened all over, cylindrically ground, first internally and then externally whereupon the cutting edges are sharpened.

The known hard mating segments, also mounted on a supporting cylinder by means of screws, have an underside and an outer side which are ground concentrically relatively to their supporting cylinder. These segments are also hardened all over. Internal grinding of the underside of the hard punching dies and of the hard mating segments must be carried out with great accuracy so that the undersides are completely flush on the associated supporting cylinders. Failure to do so would prevent the punching dies from cutting correctly. Precise internal grinding of the segmental parts of hardened steel or even hard metal is very time consuming and costly.

The punching dies and mating segments must have a circumferential speed which is identical to the conveying speed of the paper which is to be cut. The permissible wear of the cutting edges of a punching die is therefore limited to approximately 0.8 mm below the desired radial dimension referred to the axis of rotation. This also applies to the mating segments.

Attempts have been made to shim excessively worn punching dies with sheet metal or the like. However, in this case neither the underside nor the cutting edges will be disposed concentrically relative to the supporting cylinder of the punching die. Even if the cutting edges of a punching die, packed with shims, are once again cylindrically ground and sharpened, the cutting is generally unsatisfactory due to the failure to bear flush upon the supporting cylinder. For this reason, punching dies whose cutting edges have worn by approximately 0.8 mm are generally replaced by fresh dies. This also applies to worn mating segments.

An object of the present invention is to eliminate these drawbacks of prior art constructions.

Another object is the provision of rotary hard punching dies and/or rotary hard mating segments which can be made at a lower cost and with a more accurate undersidethan existing constructions and which can be restored after excessive wear at a comparatively low cost, whereby the cutting operation of the reconditioned parts will be equivalent to the cutting operation of new parts.

Other objects of the present invention will become apparent in the course of the following specification.

In the accomplishment of the objectives of the present invention it was found desirable to provide a layer of curable synthetic resin, for example, an epoxy resin, and to permanently attach this layer to the cylindrical underside of the rotary punching die and/or rotary mating segment which bear firmly upon a supporting cylinder.

The use of such a packing or coating of a curable synthetic resin upon a punching die or a mating segment consisting entirely of steel and ground in the usual manner on the cylindrical underside, as suggested by the present invention, has the following advantages:

The costly internal grinding of the hardened parts is eliminated. The underside of the unhardened parts is merely machine turned to a radius which is approximately 1 mm larger than the external radius of the supporting cylinder and is preferably provided with grooves to ensure better adhesion of the synthetic resin packing. Starting from the underside, the exterior is machined on a mandrel of appropriate diameter. The parts which are finished except for the external grinding are then hardened. The hardened parts are then placed upon a device concentrically to a mandrel of the precise diameter of the subsequent supporting cylinder so that sufiicient grinding allowance is left on the cutting edges of the punching die or the external surface of the mating segment after which the space between the underside of the parts and the mandrel is cast with synthetic resin. After the synthetic resin is cured, the underside of the parts will be firmly joined to a synthetic resin packing which has the precise radius of the subsequent supporting cylinder. External grinding which then follows is carried out in the usual manner on a mandrel having the diameter of the supporting cylinder.

When a punching die coated in accordancewith the invention is excessively worn it is reconditioned as follows:

The plastics resin packing is removed. The punching die is then held in the same device so that sufficient grinding allowance for a renewed circular grinding operation and sharpening operation is availableon the worn cutting edges concentrically to the of rota- .tion of the punching die. Subsequently, the space between the underside of the punching die and a man-- drel of the precise diameter of the supporting cylinder, placed into the device, is once again filled with a curable synthetic resin. The synthetic resin layer will then be thicker than the synthetic resin layer of the first packing of the new punching die by the amount equivalent to the preceding wear and the grinding allowance. The cutting edges of the punching die provided with the thicker synthetic resin packing are then subjected to circular grinding and sharpening in the same way as for new punching dies.

Worn punching dies can be reconditioned in this manner until the cutting edges do not project sufficiently from the segmental punch body. Mating segments whose outer surface is excessively worn are provided with a thicker synthetic resin packing in the same manner as described above and are then cylindrically ground on the exterior after being fitted on to a mandrel.

The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawings showing by way of example only, preferred embodiments of the inventive idea.

IN THE DRAWINGS FIG. 1 is a cross-section through a prior art embodiment of a punching die for the cutting out of window openings and of a mating segment cooperating therewith together with the associated supporting cylinders;

FIG. 2 is a plan view of a punching die for the cutting out of window openings according to the present inven-- tion;

FIG. 3 is a section along the line III III of FIG. 2;

FIG. 4 is a partial section along the line IV IV of FIG. 3;

FIG. 5 is a plan view of a mating segment according to the present invention;

FIG. 6 is a section along the line VI VI of FIG. 5;

FIG. 7 is a plan view of an apparatus having a punching die inserted therein for packing;

FIG. 8 is a side view of FIG. 7, partially sectioned along the line VIII VIII of FIG. 7;

FIG. 9 is a section along the line IX IX of FIG. 7 ,and

FIG. 10, 11 and 12 show mandrels of the apparatus together with supports.

FIG. 1 shows a supporting cylinder 1 rotating in the direction of the arrow and having mounted thereon by means of screws 3 a punching die 2 of known construction for the cutting of approximately rectangular window openings in a strip of paper P moving in the direction of the arrow. As illustrated in FIG. 3, the

punching die is provided with longitudinal cutting edges 4, extending approximately parallel to the axis of rotation of the supporting cylinder 1, transverse cutting edges 5 and arcuate cutting edges 6, all of which are arranged on a cylindrical surface which is concentric with the supporting cylinder. A mating segment 7 is mounted by screws 8 on a supporting cylinder 9 which rotates in the direction of the arrow. The external surface 10 of the mating segment is shaped as cylindrical surface which is concentric with the supporting cylinder 9. Filler segments 11, the outer surfaces of which are soft, may be provided on the supporting cylinder 9 to complete the shape of the cylindrical surface. During its passage between the hard surface 10 of the mating segment and the cutting edges 4, 5 and 6 of the punching die 2 which touches the mating segment, the paper P is cut, the paper speed and the circumferential speed of the cutting edges of the punching die and ofthe mating segment being the same.

FIGS. 2 to 4 illustrate a punching die made in accordance with the present invention. The same numerals are used as those in FIG. 1. As shown in FIG. 2, the longitudinal cutting edges 4 are inclined in a known manner relative to the axis of rotation of the supporting cylinder 1 at a small angle d of approximately 2 30'in order to avoid that the longitudinal cutting may strike the mating segment with a severe impact. Arcuate cutting edges 6 are provided between the longitudinal cutting edges 4 and the transverse cutting edges 5. The cutting edges 4, 5 and 6 are machined by milling away the adjacent material to a lower cylindrical surface 12. Countersunk holes 13 are provided for the mounting screws 3. The packing 15 of curable synthetic resin is fixedly joined to the underside of the punching die which is suitably roughened by means of grooves 14 which are machine turned therein in threaded manner. On the underside, the synthetic resin has the precise radius R of the supporting cylinder 1. After the packing 15 is mounted on-a mandrel having the precise diameter of the supporting cylinder 1, the cutting edges 4, 5 and 6 are cylindrically ground and sharpened.

FIGS. 5 and 6 show a mating segment 7, coated in accordance with the present-invention, whose underside is also suitably roughened by means of grooves 14 and which is fixedly joined to a backing 16 of curable synthetic resin. On its underside the backing has the precise radius R of the supporting cylinder- 9. Countersunk holes 17 are provided for the mounting screws 8. The cylindrical external surface 10 of the mating segment is cylindrically ground to the required diameter on a mandrel of the precise external diameter of the supporting cylinder 9 only after the backing 16 is applied.

The apparatus shown in FIGS. 7 to 9 for attachin the backing to apunching die or mating segment has a base plate 20 on which tow clocks 21 with accurately, aligned supports 22 are mounted by means of screws 23 and dowel pins 24. Two plates 26 with upper indentations 27 and two holders 28 for cover plates 29, which are slidable in their plans and are thrust upwardly by light springs 30 are adapted to slide in the alignment direction of the supports 22 and may be clamped on the base plate 20 by means of screws 25. The cover plates have an arcuate opening 31 the radius of which is identical to that of the supporting cylinder 1 or 9, respectively.

The alignment mandrel 32 illustrated in FIG. 10 is provided in its middle part with two axially slidable discs 33 which can be clamped by means of screws 34. The discs 33 have an external diameter D' which corresponds to the internal radius R of a punching die 2 or mating segment 7 which is not yet provided with the packing, that is to say is larger by twice the desired packing thickness than the diameter D of the supporting cylinder. The two concentric journals 36 of the mandrel have a diameter d.

The middle part of the core mandrel 35, forming the supporting surface on the supporting cylinder for the synthetic resin packing, has a diameter D equal to the diameter of the supporting cylinder 1 or 9, respectively,

. on the assumption that their diameters are identical.

after the discs 33 are set in accordance with the length of the punching die. A layer 42 of prepared plaster of Paris or the like is applied to the upper indentations 27 of the abutrnents 26 of the apparatus, whereupon the mandrel 32 together with the punching die 2 mounted thereon is inserted into the blocks 22 of the apparatus, so that the downwardly disposed cutting edge side of the punching die becomes embedded in the soft plaster of Paris or the like. After the plaster of Paris has set, the punching die will be secured on the abutments. The adhesive tape 41 is then cut through and the alignment mandrel 32 is lifted.

The cover plates 29 are then pushed against the end sides of the punching die and their holders 28 are clamped. The punching die is then ready for receiving the backing. The synthetic resin, mixed with a hardener is poured on to the underside of the punching die, said underside facing upward in the apparatus, and immediately thereafter, the core mandrel 35, treated with a parting medium, is inserted into the blocks of the apparatus. The core mandrel expels excess synthetic resin from the open longitudinal sides of the punching die. The core mandrel 35 remains in the apparatus until the synthetic resin backing has sufficiently hardened to enable the mandrel to be lifted off without damaging the backing. The synthetic resin backing, adhering firmly to the punching die then merely requires deburring of the side edges and drilling of the mounting holes 13. The backed punching die is then ready for cylindrical grinding and sharpening of its cutting edges.

If a substantially worn punching die is to be provided with a thicker, eccentric backing for the purpose of reconditioning, the punching die, freed of its previous backing, is aligned in the apparatus by means of the alignment mandrel 32 in the manner described hereinabove. Sine the plastic resin backing must be thicker than the backing of the new punching die by the amount of wear in addition to the grinding allowance, it follows that the core mandrel 35 must then be positioned correspondingly higher in the apparatus than the alignment mandrel 32. Supports 43, placed under the journals 39 of the core mandrel 35 on to the blocks 22 (FIG. 12) are provided for this purpose. The thickness of the supports 43 for 90 blocks is approximately 0.7 mm if the mandrel is to be positioned higher by 1 mm. If loose supports are to be avoided, the journals 36 of the alignment mandrel 32 may have a diameter which is less than twice the thickness of the supports 43 for providing eccentric backing to punching dies which are to be reconditioned; alternately, the journal 39 of the core mandrel may have a correspondingly thicker diameter. The same applies to the provision of a backing on mating segments.

The apparatus for backing new or worn punching dies or mating segments is not confined to the embodiment described herein. Another embodiment in which a punching die or mating segment is aligned and fixed in accordance with its internal radius R and is then provided by means of a core with a backing having the precise internal radius of its supporting cylinder, is also within the scope of the present invention.

I claim:

1. Apparatus for attaching a backing to the underside of a rotary punching die or of a mating segment carried 2} supportin cylinders, said apinraratus comprising med suppo an alinement man the die or segment, a core mandrel, each of said mandrels being adapted to be removably mounted on said supports, slidable abutments between said supports, and a layer of a plastic compound upon said abutments, said plastic compound being adapted to hold the outer surface of the die or segment, whereupon the die or segment carrying alinement mandrel is removed to expose the inner surface of the die or segment for the application of the bearing, whereupon the core mandrel is of the backing than that of a supporting cylinder, thediameter of the core mandrel being equal to that of the supporting cylinder.

2. Apparatus in accordance with claim 1, comprising supports supporting the core mandrel at a higher level than the first-mentioned supports in case of a substantially worn punching die or mating segment.

3. Apparatus in accordance with claim 1, wherein said mandrels have journals supporting them upon said supports, the diameter of the journal of the alinement mandrel being different from that of the core mandrel, the difference between the two diameters being greater than the thickness of the backing in case of substantially worn die or segment.

e1 adapted to carry 

1. Apparatus for attaching a backing to the underside of a rotary punching die or of a mating segment carried by supporting cylinders, said apparatus comprising alined supports, an alinement mandrel adapted to carry the die or segment, a core mandrel, each of said mandrels being adapted to be removably mounted on said supports, slidable abutments between said supports, and a layer of a plastic compound upon said abutments, said plastic compound being adapted to hold the outer surface of the die or segment, whereupon the die or segment carrying alinement mandrel is removed to expose the inner surface of the die or segment for the application of the bearing, whereupon the core mandrel is applied to engage the backing, the diameter of the alinement mandrel being larger by twice the thickness of the backing than that of a supporting cylinder, the diameter of the core mandrel being equal to that of the supporting cylinder.
 2. Apparatus in accordance with claim 1, comprising supports supporting the core mandrel at a higher level than the first-mentioned supports in case of a substantially worn punching die or mating segment.
 3. Apparatus in accordance with claim 1, wherein said mandrels have journals supporting them upon said supports, the diameter of the journal of the alinement mandrel being different from that of the core mandrel, the difference between the two diameters being greater than the thickness of the backing in case of substantially worn die or segment. 